Propeller



- Sept. 9, 1930. 5, MCFARLAND 1,775,315

PROPELLER Filed March 27, 1929 Patented Sept. 9, 1930 UNITED STATES PATENT; OFFICE JAMES S. MGFARLAND, OF WOOLWICH, MAINE, ASSIGNOR OF ONE-THIRD '10 CHARLES HENRY BUTLER, OF WASHINGTON, DISTRICT OF COLUMBIA PROPELLER Application filed March 27, 1929. Serial No. 350,265.

The object of this invention is to so construct each blade of a propeller that more power or thrust and more speed are obtained with any given speed of rotation of the propeller, as more fully hereinafter set forth.

In the drawing- Fig. 1 is a face view of the propeller;

Fig. 2 is a back view thereof;

Fig. 3 is a side view of the blade.

Fig. 4 isa cross-section of the blade at its greatest width, taken on line 4-4 of Fig. 2.

Referring to the drawing annexed by reference-numerals, 5 designates the usual hub and v 6 designates the usual blade, shaped in the present instance for marine purposes. With- 1n the margin of the blade is formed a hole 7, and back of this hole is formed a supplemental blade 8 whose forward edge merges smoothly into the body of the main blade at the. front edge of the aforesaid hole.

'This supplemental blade extends backwardly at an acute angle to the main blade and covers the entire hole in the main blade. This supplemental blade is not'as large in area as the main blade, but it extends practically to therear or'leaving edge of the main blade and has its edge shaped to generally conform to the main blade. The face of this landing on a shorter field. It will be understood that for both marine propellers and air propellers, I may increase the number of supplemental blades, if such increase be found desirable, without departing from my inven tion.

What I claim as new is: y A propeller having each of its main blades provided with a hole formed within the margin line of the blade approximately at its center and approximately of the same contour as the main blade, each of said main blades having a supplemental blade arranged behind said main blade and having its forward edge merged into the forward edge of said hole and being extended backwardly at an. acute angle to the main blade and beyond the rear edge of said hole so as to have a greater active area than said hole, as substantially set forth.

In testimony whereof I hereunto aflix my signature.

JAMES S. MoFARLAND.

supplemental blade also conforms substan-.

tially to the face of the main blade. In operatlon, a portion of the water that impinges against the face of the main blade will be di- I 'rected through the hole in the main blade and along against the front faceof the supplemental blade, spreading out over the entire area thereof. By reason of this division of the water stream and spreading a part of the water under pressure out over the surface of the supplemental blade, I greatly increase the power or thrust of, the propeller and am thus enabled to obtain an increaseof speed of the boat with any given speed of rotation of the ropeller-shaft.

It will be olIvious that my invention is adapted to air-craft propellers without sacrificing any of the advantages thereof. My propeller will be particularly desirable for use on aeroplanes in that it will enable the plane to hop ofi in a shorter distance without racing the motor and it will-also permit- 

